CodeJunkie, I agree with k-ww. The majority of manufacturers of ICs supply a recommended circuit either in the datasheet or application notes, which will tell you the type and value used for capacitors. These values do not necessarily tie in with the theory (and in many cases you won't get enough information to calculate it).

For example, the datasheet for the LM7805 linear regulator converting 9V to 5V says to use 0.33uF for input, and 0.1uF for output. Although the notes in the datasheet also implies that the output capacitor is not absolutely necessary for it to work, it'll just work better with it there.

From a practical point of view, you probably don't want to have to buy every single capacitance value that a datasheet might suggest you use, so knowing a bit of theory would let you make an educated guess as to whether it's ok to use the nearest higher or nearest lower value as a substitute.

My advice to you is to learn the theory if you can, but don't get too hung-up about it (unless you're doing precise oscillators, or filters, or power circuits), and go with the datasheet recommended values

You may or may not find this site helpful http://www.allaboutcircuits.com/ Don't forget to search at you tube. I have been placing the Navy Electricity Electronics Technical Series modules on http://www.archive.org search for neets, and while you are there also search the video section for army or navy training videos on the subjects. Also doing a web search for neets should find where you can read the modules online. I have to admit I don't have all the modules loaded up to archive.org yet. While the why is under too much information, the last time I tried a marathon session, I ended spending 3 day in hospital. Hope this helps some a little.

Capacitors can make great timers too; I use a 0.1uF capacitor to time the pulses from a 555 in my PWM fan controllers. It charges up to a digital 1, triggers the circuit, gets discharged to a digital 0, and repeats. I can speed up the rate with a smaller cap, or slow it down with a larger cap; to me it is an analog electronic hourglass. Somehow I doubt this is what they imagined capacitors would be used for when they were first created, but it works great. Of course I also use them for power regulation on sensitive circuits and with inputs that are not regulated.

I have found associating animation with another search term is helpful in finding animations and videos showing how something works i.e. [ animation inductor] . While inductors , and capacitors can be useful in DC only circuits, it's in AC circuits than they really do a lot of work for us. Reactance is a resistance to AC current, capacitors, and inductors are reactive components., In AC circuits, they resit current flow in a manner they do not in DC circuits. Radio Waves are AC, in radio transmitter, receivers is where capacitors do a lot of magic for us. For excellent printed material on the topic go to http://www.archive.org and search for neets, I have uploaded most of the Navy (USA) Electricity Electronics Training Series to there.http://www.allaboutcircuits.com/videos/index.htmlhttp://electricalway.blogspot.com/2011/ ... jw/AC.htmlThose are a few of many

If you're using a capacitor for "smoothing" a power supply, in my experience you can't have too much capacitance: bigger is generally better. The main reason capacitors exist in specific values is for tuned LC circuits, which use a capacitor and an inductor. These have a resonant frequency determined by the values of the capacitor and inductor. They are extremely important in radios, oscillators, tesla coils, etc. Wikipedia does a pretty good job of explaining them: http://en.wikipedia.org/wiki/LC_circuit